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124 lines
6.9 KiB
124 lines
6.9 KiB
# Helper to allocate a stream on the heap. |
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== code |
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# instruction effective address register displacement immediate |
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# . op subop mod rm32 base index scale r32 |
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# . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes |
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new-stream: # ad: (addr allocation-descriptor), length: int, elemsize: int, out: (addr handle stream _) |
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# . prologue |
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55/push-ebp |
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89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp |
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# . save registers |
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50/push-eax |
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52/push-edx |
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# var size/edx: int = elemsize*length (clobbering eax) |
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# . eax = elemsize |
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax |
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# . eax *= length |
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31/xor 3/mod/direct 2/rm32/edx . . . 2/r32/edx . . # clear edx |
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f7 4/subop/multiply 1/mod/*+disp8 5/rm32/ebp . . 0xc/disp8 . # multiply *(ebp+12) into edx:eax |
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# . if overflow abort |
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81 7/subop/compare 3/mod/direct 2/rm32/edx . . . . . 0/imm32 # compare edx |
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75/jump-if-!= $new-stream:abort/disp8 |
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# . edx = elemsize*length |
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89/copy 3/mod/direct 2/rm32/edx . . . 0/r32/eax . . # copy eax to edx |
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# var n/eax: int = size + 12 (for read, write and size) |
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05/add-to-eax 0xc/imm32 |
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# allocate(ad, n, out) |
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# . . push args |
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ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x14/disp8 . # push *(ebp+20) |
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50/push-eax |
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ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) |
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# . . call |
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e8/call allocate/disp32 |
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# . . discard args |
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp |
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# eax = out->payload |
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x14/disp8 . # copy *(ebp+20) to eax |
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8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax |
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# skip payload->allocid |
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05/add-to-eax 4/imm32 |
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# eax->size = size |
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89/copy 1/mod/*+disp8 0/rm32/eax . . . 2/r32/edx 8/disp8 . # copy edx to *(eax+8) |
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# clear-stream(eax) |
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# . . push args |
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50/push-eax |
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# . . call |
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e8/call clear-stream/disp32 |
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# . . discard args |
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp |
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$new-stream:end: |
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# . restore registers |
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5a/pop-to-edx |
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58/pop-to-eax |
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# . epilogue |
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89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp |
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5d/pop-to-ebp |
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c3/return |
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$new-stream:abort: |
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(abort "new-stream: size too large") |
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# never gets here |
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test-new-stream: |
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# . prologue |
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55/push-ebp |
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89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp |
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# var ad/ecx: allocation-descriptor containing 16 bytes |
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# . var end/ecx: (addr byte) |
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89/<- %ecx 4/r32/esp |
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# . var start/edx: (addr byte) = end - 32 |
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81 5/subop/subtract %esp 0x20/imm32 |
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89/<- %edx 4/r32/esp |
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# . ad = {start, end} |
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51/push-ecx |
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52/push-edx |
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89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx |
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# var start/edx = ad->curr |
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8b/copy 0/mod/indirect 1/rm32/ecx . . . 2/r32/edx . . # copy *ecx to edx |
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# var h/ebx: (handle stream byte) |
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68/push 0/imm32 |
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68/push 0/imm32 |
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89/copy 3/mod/direct 3/rm32/ebx . . . 4/r32/esp . . # copy esp to ebx |
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# new-stream(ad, 3, 2, h) |
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# . . push args |
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53/push-ebx |
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68/push 2/imm32 |
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68/push 3/imm32 |
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51/push-ecx |
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# . . call |
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e8/call new-stream/disp32 |
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# . . discard args |
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp |
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# eax = out->payload |
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8b/copy 1/mod/*+disp8 3/rm32/ebx . . . 0/r32/eax 4/disp8 . # copy *(ebx+4) to eax |
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# check-ints-equal(eax, edx, msg) |
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# . . push args |
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68/push "F - test-new-stream: returns current pointer of allocation descriptor"/imm32 |
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52/push-edx |
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50/push-eax |
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# . . call |
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e8/call check-ints-equal/disp32 |
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# . . discard args |
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp |
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# skip payload->allocid |
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05/add-to-eax 4/imm32 |
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# check-ints-equal(eax->size, 6, msg) |
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# . . push args |
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68/push "F - test-new-stream: sets size correctly"/imm32 |
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68/push 6/imm32 |
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ff 6/subop/push 1/mod/*+disp8 0/rm32/eax . . . . . 8/disp8 # push *(eax+8) |
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# . . call |
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e8/call check-ints-equal/disp32 |
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# . . discard args |
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp |
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# the rest is delegated to clear-stream() so we won't bother checking it |
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# . reclaim locals |
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x30/imm32 # add to esp |
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# . epilogue |
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89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp |
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5d/pop-to-ebp |
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c3/return |
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# . . vim:nowrap:textwidth=0
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